Double-throw clamp tight switch



Jan. 15, 1952 A. s. CASWELL 2,582,745

DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 v Sheets-Sheet 1 INVENTOR- APH'iUI" 5. Cdswell BY W517 ATTORNEYS Jan. 15, 1952 A. s. CASWELL DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 7 Sheets-Sheet 2 ATTORNEYS Jan. 15, 1952 s, c sW 2,582,745

DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 7 Sheets-Sheet 3 INVENTOR. Aprbun 5. Cdswell ATTO YS Jan. 15, 1952 A. s. CASWELL 2,582,745

DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 7 Sheets-Sheet 4 INVENTOR. Ar fbur AS. CdSWe/l BY WWM ATTORNEYS Jan. 15, 1952 A. s. CASWELL 2,

DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 '7 Sheets-Sheet 5 INVENTOR. Arfbun SCdsweH ATTORNEYS Jan. 15, 1952 A. s. CASWELL 2, 32,7

DOUBLE THROW CLAMP TIGHT SWITCH Filed Maya, 1946 7 Sheets-Sheet e N V EN TOR.

B C d 4M WWZM (Mm/22 e54 Jan. 15, 1952 A 5, CASWELL 2,582,745

DOUBLE THROW CLAMP TIGHT SWITCH Filed May 21, 1946 '7 Sheets-Sheet '7 IN V EN TOR. Anna! 0". 6104/61. 1.

Patented Jan. 15, 1952 UNITED STATES PATENT OFFICE DOUBLE-THROW CLAMP TIGHT SWITCH Arthur S. Caswell, Philadelphia, Pa., assignor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 21, 1946, Serial No. 671,173

6 Claims. 1

My present invention relates to switchgear, and more particularly to double throw switchgear arranged to engage the movable contact with the stationary contacts in a tight clamping arrangement in each position of the double throw switch.

. Heretofore in switchgear of the knife switch type, it has been customary to provide a clamping arrangement for interengaging the movable element of the knife switch with the stationary contact. A portion of the closing movement of the switch was used to bring the movable contact or blade up into registry with the stationary contact and the remaining movement of the switch handle performed the clamping action. This type of clamping action is shown in the Scott Patent 2,246,072, assigned to the assignee of the present invention.

However. the problem becomes more complex in double throw switches where the movable contact blade has a neutral position as well as two separate contacting positions 180 apart.

Various means have been attempted to provide for adequate clamping pressure at both contacting positions of the knife blade but these have resulted either in extremely complex duplicate clamping mechanism or in having a clamped contact arrangement at one position only with the other position being subjected to only light clamping engagement.

In general, my invention contemplates a double throw'clamp tight switch provided with a screw having a nut on either end. When the operating handle is rotated about its pivot point, it-will during the first part of its movement rotate a contact blade to engage one of said terminals. Further movement of the operating handle thereafter is arranged to turn one of the nuts on the screw, which in turn operates a clamping mechanism for clamping the contact blade against the terminal with which it is associated at the time.

Provision is made so that one of the nuts is rotated when the contact blade is associated with one'of the terminals for effecting clamping, and the other of the nuts is operated when the contact blade is adjacent the opposite terminal for effecting clamping engagement thereat.

My invention specifically contemplates the utilization of a single right or left hand thread screw with two nuts actuated by cam pieces and so arranged that. on operation of the switch handle to one closed position one nut will be actuated to cooperate with the screw to drive the bridging blades together for clamping ac- 2 tion; and on operation to the other closed position, the other nut will be actuated to clamp the bridging blades across the contacts.

Accordingly, an object of my invention is to provide novel clamping means for double throw knife switches.

A further object of my invention is to provide a novel arrangement of screw members whereby a. nut at one end of the screw member is rotated to effect clamping at one terminal and the other nut is rotated for effecting clamping at the other terminal.

The foregoing and many other objects of my invention will become apparent in the following description and drawings in which Figure l is a side view of my novel double throw knife switch.

Figure 1a is a view corresponding to that of. Figure 1 showing the unclamped position of the switch and showing in dotted lines the open position of the switch.

Figure 2 is a front view in perspective partly broken away showing the clamping elements thereof.

Figure 3 is a view in perspective of the clamping elements of my novel knife switch with the switch blades clamped in the up position.

Figure 4 is a view in perspective of the clamping elements of my novel knife switch with the switch blades just prior to clamping action.

Figure 5 is a view in perspective of the clamping elements of my novel knife switch with the switch blades clamped in the down position.

Figure 6 is a schematic view partly in crosssection showing the clamp operator.

Figure '7 is a side view party in cross-section taken on line of Figure 6 showingv the up position of the elements corresponding to Figure 3.

Figure la is a view corresponding to that of Figure 7 showing the lower clamped position of the switch.

Figure 8 is a close up view ofone-half of the switch in the partially closed upper position.

Figure 9 is similar to Figure 8 but from the opposite side and showing the opposite half .of the switch in a partially closed lower position.

Figure 10 is an enlarged detail view corresponding to the dotted line position of Figure 1a.

Figure 11 is a view showing the position of the unit immediately after the position of Figure 8. s

Figure 12 is a view showing the closed position of the unit jimt following the position of Figure 3.

Referring now to Figures land 2, my novel double throw knife switch is mounted on an insulating panel I l to which are connected the upper stationary contact I2 and the lower stationary contact l3. Contacts l2 and I3 are mounted respectively on the ends of back connection studs l4 and I5 which pass through appropriate openings in the insulating panel The terminal I! for the movable contact member is also mounted at the front of the insulating panel II and is connected through an appropriate opening to its own back connection stud l8.

The contact blades 20 and 2| which form the movable bridging contact are pivotally mounted on the extension 25 of the middle contact terminal As the handle is operated from the upper position to the lower position, the contact portions 2|a and 20a of the knife switch are rotated about from the position wherein they engage the upper stationary contact |2 to the position where they engage the lower stationary contact l3.

The handle member 21 consists of a pair of side plates 28 and 29 which are also pivotally mounted at the extension 25 of the central terminal Plates 28 and 29 straddle extension 25, as shown, and are continued up to a point just below the point of registry of the handle with the contact member |2 in the up position or contact member l3 in the down position, at which point they are re-entrantly bent at 30, 3| and secured together to form an extension 32 which passes up between the bifurcated contact member l2 or l3. A suitable handle 34 is secured to the extension 32.

The handle plates 28 and 29 are provided with the registering slots 40 through which the pins 4| of the contact blade operating links 42 and 42a pass. Contact blade operating links 42 and 42a are each provided with a cam follower 43 and 43a at their lower ends.

The upper end 44 of link 42 is secured to cylindrical nut 5|, and the upper end 44a of link 42a is secured to cylindrical nut 5|a. Screw 10, a multiple right hand thread screw, is threaded at opposite ends into each of the nuts 5| and 5|a.

A spring eye 45a has an opening receiving the portion of screw between nuts 5| and Ella. Tension springs 45 are connected at their lower ends to spring eye 45a and at their upper ends to cross-bar 46a on pin 46 carried between handle plates 28 and 29.

Handle plates 28 and 29 are each provided with curved parallel slots 50 through which nuts 5| and 5|a pass. Nut 5| is secured by bolt 63 to clamping plate 64. Nut 5|a is secured by bolt 65 to clamping plate 66.

The central extension 25 from the central terminal I1 is provided with the pair of cams 80 and 8|. Each of the cams has a recess 82 and the cams 86 and 8| which are parallel to each other are spaced from each other by the extension 25a. 7

In the neutral or open position of the switch,

as shown by the dotted lines of Figure 1a, the

cam followers 43 and 43a of links 42 and 42a register in the central depression or curve 82 of their respective cams 80 and 8|. Tension springs 45 act as centering springs to hold the handle assembly 21 in horizontal position.

When it is desired to close the switch to the up position of Figure 1, handle 34 is pushed up rotating the assembly 21 about the pivot 9|. Since the pins 4| and Ma of links 42 and 42a are held in slots 40 of handle plates 28 and 29, motion is transmitted to the links 42 and 42a through appropriate rollers on the pins 4| and He and the links are also rotated upwardly. Since, however, cam followers 43 are held in recess 82, the upper ends 44, 44a of links 42 move up faster than the pins 4| and the handle assembly 2'1. This moves the nuts 5| and 5|a and the screw 16 rapidly toward the left in the slots 56 of the handle assembly faster than the handle is being moved by hand. This extends the tension springs 45 and at the same time causes the contact blades 20 and 2| to move up ahead of the handle assembly 2! to contacting position.

It will be noted that the springs 45 are constantly biased since they are not on the center line of the handle assembly 21 and the pivot 9|. This has been done in order to overcome the force of gravity acting on the handle assembly 21 and the contact plates 28 and 2| and thereby hold the switch member in a horizontal position when it is open. This tension also exerts a bias on the links 4242a by tending to draw this assembly into a straightened out condition. This causes the cam followers 43-43a to bear against the cam surface 82, 85, and 84.

The slot 50 in plates 28 and 29 of the handle is arcuate about the pivot point 9| as an axis and is of such size as to allow nuts 5| and 5|a to be mounted in the plates 28 and 29, respectively, for free arcuate movement.

The slots 40 in plates 28 and 29 of the handle have a radial portion which is coaxial with a medial line drawn from the pivot 8| through the center of the handle as viewed in Figures 1 and 1a.. The slots 40 also have an arcuate portion and the arcuate portion of slot 40 in plate 28 extends oppositely from the arcuate portion of slot 46 in plate 29.

When the contact blades 28 and 2| engage contact |2 of the upper terminal, further travel in a counterclockwise or up direction of the handle assembly forces the follower 43a to roll along the upper surface 85 of cam 88. At the same time the upper portion of cam 8| has an extension 86 which prevents cam follower 43 from moving in. This is shown clearly in Figures 2, 3 and 7. Thus nut 5| which is secured to link 42 cannot rotate while nut 5|a secured to link 42a is rotated in a clockwise direction by the radial portion of slot 40 in plate 29. This draws the screw 18 into the nut 5|a, toward the left with respect to Figure 2, and thus drives the clamping plates 64 and 66 closer together to clamp the switch blades 20 and 2| together across contact l2 and terminal H.

The initial outward or clockwise movement of handle assembly 21 causes the link 4211 to rotate in a counterclockwise direction thus driving the nut 5|a off the screw 10 to loosen the clamps 64 and 66; and further clockwise and down rotation of handle assembly 21 brings the switch elements back to the neutral or open position.

When the switch handle assembly 21 is rotated down to engage contact l3, then follower 43 of link 42 is free to roll over the lower cam surface 88 of cam 8| as shown in Figures 5 and 7a, while follower 43a of link 42a is stopped by cam extension 89. In this case, nut 5|a is halted from rotation while counterclockwise rotation of link 42 and nut 5| draws the screw 10 into the nut 5|, thus drawing the clamping plates 64 and 66 together to force the switch blades 20 and 2| into close bridging contact across contact l3 and terminal I1.

The reverse action occurs as above described when the switch is opened from the down position back tothe neutral position.

Handle 34 is pivotally mounted on handle extension 32 by the pin 96, and held in a vertical position by the centering springs 94, 94. The pin 96 engages spring latch 91 in the up position or spring latch 98 in the down position. This prevents blowing off of the contacts onaexcessive current condition and accidental opening of the contacts on the occurrence of physical shock.

When the handle 34 is grasped to open the switch. it rotates about the pin 96 causin the ledge 95 to lift the latch 91 or 98 and thus frees the handle assembly 2'! for movement.

It will thus be seen that by the simplified construction shown, a single right or left hand screw 19 cooperating with two nuts 5| and 5m may be used to clamp the switch blades tightly across the contacts in either the up or down position.

In moving to the up position, nut 5| is held stationary while nut 5la is rotated to draw in the screw 10. This action takes place in the last few degress of counterclockwise rotation of the handle assembly 21. In moving to the down position, nut 5Ia is held stationary and nut 51 is rotated to draw the screw in to clamp the switch blades together. The links 42 and 42a which operate the nuts are held in appropriate centering position by the coil spring 99, extension 99a of which engages link 42 and extension 991) of which engages link 42a. This tends to center the links 42 in the neutral position or in any intermediate position up to the clamping positions but nevertheless permits link 42 or link 42a as the case may be, to operate its associated nut to appropriate clamping position.

In the foregoing I have described my invention solely in connection with a specific preferred embodiment thereof. Since many variations and modifications of my invention should now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosure herein contained but only by the appended claims.

I claim:

1. In a clamp tight double throw switch, a pair of terminals, a contact blade, an operating handle for said blade, a single screw having two nuts threaded thereto on opposite ends of said screw, a pair of contact operating links, a cam follower for each of said links, one end of each of said links being secured to an individual one of said nuts, a pair of tension springs secured at one end to said screw and at their other ends to said operating handle, a pair of clamping plates, each of said nuts being secured to an individual clamping plate, a cam individual to each of said cam followers each having a recess, said cam followers registering in its associated recess when said operating handle is in neutral position, said springs acting as centering springs to maintain said handle in its neutral position, said links being movable in response to a movement of said handle toward either of said terminals, means controlled by said cams and cam followers for efiecting through said links more rapid movement of said contact blade than the movement of said handle to effect engagement of said terminal before completion of movement of said handle, means controlled by one of said cams responsive to further movement of said handle for rotating its associated nut on said screw, the movement of said nut operating one of said clamping plates to clamp said contact blades against said terminal, and means whereby the particular nut operative is selectively dependent on the terminal engaged by said contact blade.

2. In a clamp tight double throw switch, a pair of terminals, a contact blade, an operating handle for said blade, a screw having anut on opposite ends thereof, including a pair of contact operating links, a pair of tension springs secured at one end to said screw and at their other ends to said operating handle, a cam individual to each of saidlinks, said springs acting ascentering springs to maintain said handle in its neutral position, said linksbeing movable in response to a movement of said handle toward either of said terminals, means controlled by said cam and cam followers for effecting through said links more rapid movement of said contact blade than the movement of said handle to effect engagement of said terminal before completion of movement of said handle, means controlled by said handle during the remainder of its movement for operating one of said nuts, and a pair of clamping plates, each secured to said nuts and controlled by the operation of said nuts for clamping said contact blade against said terminal.

3. In a clamp tight double throw switch, a pair of terminals, 2. contact blade, an operating handle for said blade, a screw having a nut on opposite ends thereof, a pair of contact operating links controlled by said handle during a portion of its movement for operating said contact blade to engage one of said terminals, a cam mechanism controlled by said handle during the remainder of its movement for operating one of said nuts, and a clamping plate controlled by the operation of said nut for clamping said contact blade against said terminal, the other of said nuts being operated when said contact blade has been moved to engage the other of said terminals.

4. In a clamp tight double throw switch, a pair of terminals, a contact blade, an operating handle for said blade, a screw having a nut on opposite ends thereof, a pair of links controlled by said handle during a portion of its movement for operating said contact blade to engage one of said terminals, a cam controlled by said handle during the remainder of its movement for operating one of said nuts, and a pair of clamping plates controlled by the operation of said nut for clamping said contact blade against said terminal, the other of said nuts being operated when said contact blade has been moved to engage the other of said terminals, said cam mechanism being individual to each of said terminals and nuts and operating said nuts individually in accordance with the terminal engaged by said contact blade.

5. In a clamp tight double throw switch, a pair of terminals, a contact blade, an operating handle for said blade, a screw having a nut on opposite ends thereof, a cam mechanism, means including said cam mechanism controlled by said handle during a portion of its movement for operating said contact blade to engage one of said terminals, means including said cam mechanism controlled by said handle during the remainder of its movement for operating one of said nuts, and means controlled by the operation of said nut for clamping said contact blade against said terminal, said cam mechanism being individual to each of said terminals and nuts and operating said nuts individually in accordance with the terminal engaged by said contact blade, the other of said nuts being operated when said contact blade has been moved to engage the other of said terminals.

6. In a clamp tight double throw switch, a pair of terminals, a contact blade, an operating handle for said-blade, a screw having a nut on opposite ends thereof, a cam mechanism, means including said cam mechanism controlled by said handle during a portion of its movement for operating said contact blade to engage one of said terminals, means including said cam mechanism controlled by said handle during the remainder of its movement for operating one of said nuts, and means controlled by the operation of said nut for clamping said contact blade against said terminal, said cam mechanism being individual to each of said terminals and nuts and operating said nuts individually in accordance with the 1 terminal engaged by said contact blade, the other of said nuts being operated when said contact blade has been moved to engage the other of said terminals, said cam mechanism being individual to each of said terminals and nuts and operating said nuts individually in accordance with the terminal engaged by said contact blade.

ARTHUR S. CASWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 473,134 Soden Apr. 19, 1892 488,740 Pattison Dec. 27, 1892 10 1,850,771 Raney Mar. 22, 1932 1,929,049 Austin Oct. 3, 1933 2,234,563 Kneass Mar. 11, 1941 2,288,134 Hoye June 30, 1942 5 FOREIGN PATENTS Number Country Date 15,216 Great Britain of 1888 391,249 Great Britain Apr. 27, 1933 OTHER REFERENCES Automatic Reclosing Circuit Breaker Co.

Bulletin No. 200-1129. 

